1. Field of the Invention
The present invention relates to a high internal aqueous phase water-in-oil type emulsion cosmetic composition superior in useability and stability, in particular superior in feeling of change of aqueous phase. More specifically, the present invention relates to a high internal aqueous phase water-in-oil type emulsion cosmetic composition containing at least 50.0% by weight of an aqueous phase component and superior in useability, that is, when applied to hair or the skin, instantaneously changing in aqueous phase, superior in feeling of release of water, giving moisture to the hair or skin, having a damp feel, free from stickiness, light in spreadability and superior in stability, that is, superior in the stability with the elapse of time and superior in the stability to physical stimulus.
2. Description of the Related Art
In general, an emulsifying agent is used to make a water-in-oil type (W/O) type emulsion cosmetic composition having water dispersed in the oil of the continuous aqueous phase. As such an emulsifying agent, in the past, a glyceryl fatty acid ester, sorbitan aliphatic acid ester, or other polyhydric alcohol fatty acid ester-based surfactants or polyoxyalkylene-modified organosiloxane-based surfactants has been generally used.
Generally, in a high internal aqueous phase W/O type emulsion containing more than 50% by weight of water in the composition, however, at low temperatures, the continuous oil phase easily separates due to flocculation of drops of water. Conversely, at high temperatures, the drops of water combine to cause particles to increase and precipitate and the top portion to become only an oily component for easy separation of the oil phase again. Various proposals have already been made to reduce this instability due to temperature by formulating in large amounts of waxes to increase the consistency, but even these have been insufficient in that there was incomplete stability at high temperatures. Further, since W/O type emulsions have oil components as external phases, they are advantageous in protecting the skin or imparting softness, but suffer from problems in useability such as stickiness at the time of use, heaviness in spreadability, and hardness.
It is desirable to select and blend a preferable oil ingredient from a broad range from polar oils to nonpolar oils with a high internal phase ratio, but it was not possible to obtain a stable water-in-oil type emulsion cosmetic composition of a system including a polar oil using a conventional polyol fatty acid ester-based activant or of a system including a nonpolar oil with a polyoxyalkylene-modified organopolysiloxane-based active agent. Therefore, there were restrictions on the selection of the oil component in conventional water-in-oil type emulsion cosmetic compositions and, it was impossible to achieve broader based popularity due to the feeling in the application.
To eliminate these problems in useability and stability, a composition is sought which has a high internal aqueous phase ratio, which, when applied onto the skin or hair, has emulsion particles break down instantaneously simultaneous with the application and release the water in the internal aqueous phase, and which is excellent in the stability with the elapse of time. However, at the present time, while it is possible to use the polyol fatty acid ester-based surfactants or polyoxyalkylene-modified organopolysiloxane-based surfactants which had been used as W/O type emulsifying agents in the past so as to prepare a high internal aqueous phase W/O type emulsion cosmetic composition, the problem in the area of the stability with the elapse of time cannot be solved.
Among these, a paste-like polyether-modified silicone composition obtained by processing the cross-linkable polyether-modified silicone of the structural formula (I) or (II) used in the present invention with silicone oil has recently been developed. The technique of producing a water-in-oil type emulsion composition superior in the stability with the elapse of time and application feeling using this composition has already been proposed. Further, a water-in-oil type emulsion composition improved in useability by formulating in a large amount of water has been proposed. Inclusion of silicic acid anhydride or hydrophobic silica to keep the stability with the elapse of time has also already been proposed (Japanese Unexamined Patent Publication (Kokai) No. 6-40847).
It is desirable that such a water-in-oil type emulsion composition have stability for the pipeline transport required for continuous production in addition to the aforesaid properties, that is, the useability and stability, or stability in use when repeatedly extruded for use, but if physical stimulus is given, such as in a vibration test or tube squeezing test to confirm it, there has been the problem that the emulsion is broken down and the internal aqueous phase component is released even with a composition produced by the proposed methods.